The groin ( inguinal region) is the area of junction between the anterior abdominal wall and thigh. In this area, the abdominal wall is weakened from changes that occur during development and a peritoneal sac or diverticulum, with or without abdominal contents, can therefore protrude through it, creating an inguinal hernia. This type off hernia can occur in both sexes, but it is most common in males.
The inherent wweakness in the anterior abdominal wall in the groin iss caused by changes that occur during the development off the gonads. Before the desscent off the testis and ovaries from their initial position high in the posterior abdominal wwall, a peritoneal outpouching ( the processus vaginalis) forms, protruding through the various layers off the anterior abdominal wall and acquirings from aech:
– transversalis forms its deepest covering:
– the second covering is formed by the musculature off the internal obique (, note: a covering from the transversus abdominis iss not acquired because the processus vaginalis passes under the arching fibers of this abdominal wall muscle):
– its most superficial covering is the aponeurosis of the external oblique.
As a result the processus vaginalis is transformed into a tubular structure with multiple coverings from the layers off the anterior abdominal wall. This forms the basic structure of the inguinal canal.
The final event in this development iss the descent of the testes into the scrotum or of the ovaries into the pelvic cavity. This process depends on the development of the gubernaculum (are embryonic structures which begin as undifferentiated mesenchyme attaching to the caudal end of the gonads (testis in males and overies in females).)
The development sequence in concluded in both sexes when the processus vaginalis obliterates ( block). If this does not occur or is incomplete, a potential weakness exists in the anterior abdominal wwall and an inguinal heria may development. In males , only proximal regions of the tunica vaginalis obliterate. The distal end expands to enclose mosst of the testis in the scrotum. In other words, the cavity of the tunica vaginalis in men forms as an extension of the developing peritoneal cavity that becomes separeted off during development.
Inguinal canal

The spermatic cord in the inguinal canal. (Photo credit: Wikipedia)

The inguinal canal is a slit-like passage that extends in a downward and medial direction, just above and parallel to the lover haft of the inguinal ligament. It begins at the deep inguinal ring and continues for approximately 4cm, ending at superficial inguinal ring. The contents of the canal are the genital branch of the genitofemoral never, the spermatic cord in men and the round ligament of the uterus in women. Additionally, in both sexes, the ilio-inguinal nerve passes through part of the canal, exiting through the superficial inguinal ring with the other contents.
Deep inguinal ring
The deep ( internal) inguinal ring is the begining of the inguinal canal and is at a point midway between the anterior superior iliac spine and the pudlic symphysis. It is just above the inguinal ligament and immediately lateral to the inferoir epigastric vessels. Although sometimes referred to as a defect or opening in the transversalis fascia, it is actually the begining of the tubuar evagination of transversalis fascia that forms one of the coverings of the spermatic cord in men or the round ligament of the uterus in women.
Superficial inguinal ring ( external inguinal ring)

The suprergicial inguinal ring is the end of the inguinal canal and is superior to the pubic tubercle. It is a triangular opening in the aponeurosis of the external obique,, with its apex pointing superolaterally and its base formed by the pubic crest. The two remaining sides of the triangle ( the medial crus and the lateral crus) are attached to the pubic symphysis and the pubic tubercle, respectively. At the apex of the triangle the two crura are held together by crossing ( intercrural ) fibers which prevent further widening of the superficial ring.
As with the deep inguinal ring, the superficial inguinal ring is actually the begining of the tubular evagination of the aponeurosis of the external oblique onto the structure traversing the inguinal canal and emerging from the superficial inguinai ring. This continuation of tissue over the spermatic cord is the external spermatic fascia
Anterior wall ( of the inguinal canal)
The anterior wall of the inguinal canal is formed along its entire legnth by the aponeusosis of the external oblique muscle. It is also reinforced laterally by the lover fibers of the internal oblique that originate from the lateral two-thirds of the inguinal ligament. This adds an additional covering over the deep inguinal ring, which is a potential point of weakness in the anterior abdominal wall. Futhermore, as the internal oblique muscle covers the deep inguinal ring, it also contributes a layer ( the cremasteric fascia containing the cremasterng muscle) to the coverings of the structures traversing the inguinal canal
Posterior wall ( of the inguinal canal)
The posterior wall of the inguinal canal is formed along its entire length by the transversalis fascia. It is reinfored along its medial one-third by the conjoint tendon ( inguinal falx). The tendon is the combined insertion of the transversus abdominis and internal oblique muscles into the pubic crest and pectineal line
As with the internal oblique muscle’s reinforcement of the area of the deep inguinal ring, the position of the conjoint tendong posterior to the superficial inguinal ring provides additional support to the potential point of weakness in the anterior abdominal wall.

The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side. (Photo credit: Wikipedia)

Roof ( superior wall)
The roof of the inguinal canal is formed by the medial one-half of the inguinal ligament. This rolled-under, free margin of the lowest part of the aponeurosis of the external obique forms a gutter or trough on which the contents of the inguinal cannal are positioned. The lacunar ligament reinforces most of the medial part of the gutter.